Project stakeholders are entities that have an interest in a given project.

To further qualify that statement.

“A Stakeholder can be a person, a group, or an organization that may be affected positively or negatively, or have any kind interest in the project or in project’s outcome either directly or indirectly.”

“Project stakeholders are individuals and organizations that are actively involved in the project, or whose interests may be affected positively or negatively as a result of project execution or project completion.”

They may also exert influence over the project’s objectives and outcomes.

Here is the PMI definition as per 5th Edition Project Management Body of Knowledge PMBOK Guide

A Project Stakeholder is “An individual, group, or organization who may affect, be affected by, or perceive itself to be affected by a decision, activity or, an outcome of a project.

These stakeholders may be inside or outside an organization which:

It is important to identify all stakeholders whether internal or external as their opinion can influence the project outcomes.

sponsor a project or have an interest or a gain upon a successful completion of a project;
may have a positive or negative influence in the project completion.

The project management team must identify the stakeholders, determine their requirements and expectations, and, to the extent possible, manage their influence in relation to the requirements to ensure a successful project.

In a typical projects the stakeholders could be:

Internal Stakeholders

Project team members

Project Sponsors

Upper management

Project customer

Resource Managers

Line Managers

Product user group

Project testers

Any group impacted by the project as it progresses

Any group impacted by the project when it is completed

Subcontractors to the project

Consultants to the project

External Stakeholders

External clients

External customers

End users of the service or product which the project is going to produce.

Vendors

Sub-contractors

Government

Local communities

Media groups

prospective clients

political groups

Now an important and somewhat controversial question(you might hear different answers from different experts) arises- according to the definition we have said that anyone who gets positively or negatively impacted by the project outcomes could be deemed as Stakeholders !

There are differing views as PMBOK or Prince2 does not answer that.

Do your Competitors qualify as stakeholders ?

No. Though they get negatively impacted as a result of your project outcome for sure. Their opinion about your project is not helpful to shape your project .( Though the marketing teams would monitor and take into the competitors opinions to ensure that they can counter their competitors). But from a project delivery point of view the competitors may not be treated as stakeholders.

Their influence and their opinions may not directly affect the project (though you might say that competitors can cause havoc and jeopardize your project, in that sense you can include that in your risks as well :-)).

Would you be communicating your project progress to your competitors ? No

Would you take their opinion during project design or delivery ? Not exactly (however to some extend their viewpoint might affect your design )

Some experts view stakeholders as negative stakeholders. If the competitors decide to stir trouble and start interfering with your project progress then you might consider them as negative stakeholders as you would then need to manage these negative stakeholders !

From a marketing plan point of view they may be taken as negative stakeholders as the marketing plans are directly affected by competition.

From a project delivery point of view, the competitors may not be seen as stakeholders.